Memory arrays and methods of forming the same

ABSTRACT

Memory arrays and methods of forming the same are provided. One example method of forming a memory array can include forming a conductive material in a number of vias and on a substrate structure, the conductive material to serve as a number of conductive lines of the array and coupling the number of conductive lines to the array circuitry.

TECHNICAL FIELD

The present disclosure relates generally to semiconductor devices andmethods, and more particularly to memory arrays and methods of formingthe same.

BACKGROUND

Memory devices are typically provided as internal, semiconductor,integrated circuits in computers or other electronic devices. There aremany different types of memory, including random-access memory (RAM),read only memory (ROM), dynamic random access memory (DRAM), synchronousdynamic random access memory (SDRAM), resistive memory, and flashmemory, among others. Types of resistive memory include phase changememory, programmable conductor memory, and resistive random accessmemory (RRAM), among others.

Memory devices are utilized as non-volatile memory for a wide range ofelectronic applications in need of high memory densities, highreliability, and data retention without power. Non-volatile memory maybe used in, for example, personal computers, portable memory sticks,solid state drives (SSDs), digital cameras, cellular telephones,portable music players such as MP3 players, movie players, and otherelectronic devices.

Various resistive memory devices can include arrays of cells organizedin a cross point architecture. In such architectures, the memory cellscan include a cell stack comprising a storage element, e.g., a phasechange element, in series with a select device, e.g., a switchingelement such as an ovonic threshold switch (OTS) or diode, between apair of conductive lines, e.g., between an access line and a data/senseline. The memory cells are located at the intersections of a word lineand bit line and can be “selected” via application of appropriatevoltages thereto.

Performance of resistive memory cells can be affected by factors such asthe types of materials used to form the cells, the quality ofinterfaces, e.g., contact surfaces, between cell materials, and/or thenumber of interfaces present in a cell stack, among various otherfactors. Accordingly, and for various other reasons, formation ofresistive memory cells can be costly in terms of processing resourcesand time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a portion of a memory array inaccordance with a number of embodiments of the present disclosure.

FIG. 2 illustrates a cross-sectional view of a portion of a memory arrayformed in accordance with a prior art method.

FIG. 3 illustrates a cross-sectional view of a portion of a memory arrayformed in accordance with a number of embodiments of the presentdisclosure.

FIG. 4 illustrates a portion of a memory array formed in accordance witha number of embodiments of the present disclosure.

DETAILED DESCRIPTION

Memory arrays and methods of forming the same are provided. An examplemethod includes forming a substrate structure including array circuitry,forming a number of vias in the substrate structure such that a numberof portions of the array circuitry are exposed, and forming a conductivematerial in the number of vias and on the substrate structure, whereinthe conductive material serves as a number of conductive lines of thearray and couples the number of conductive lines to the array circuitry.

Embodiments of the present disclosure can provide benefits such asproviding a combined, e.g., integrated, conductive plug/conductive lineelement that serves as a connection to array circuitry, such as decodecircuitry underlying an array of memory cells. The combined conductiveplug/conductive line element can be formed of a continuous conductivematerial such that no interface separates a plug portion of the elementand a line portion of the element, which can reduce the path resistanceassociated with separately formed conductive plug/conductive linestructures, for instance. Also, various previous approaches in which aconductive plug is formed separately from a conductive line, e.g., anaccess line or data/sense line, can include performing a planarizationprocess, e.g., CMP (chemical mechanical planarization), in order toprovide a suitable contact interface between the plug and the conductiveline. Since a number of embodiments of the present disclosure caninclude forming an integrated conductive plug/conductive line, whichdoes not include an interface there between, such a CMP process betweenformation of the plug and formation of the conductive line can beeliminated, which simplifies the array formation process and reducesformation costs associated therewith.

In the following detailed description of the present disclosure,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration how one or more embodimentsof the disclosure may be practiced. These embodiments are described insufficient detail to enable those of ordinary skill in the art topractice the embodiments of this disclosure, and it is to be understoodthat other embodiments may be utilized and that process, electrical,and/or structural changes may be made without departing from the scopeof the present disclosure.

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. For example, 210 may referenceelement “10” in FIG. 2, and a similar element may be referenced as 310in FIG. 3. Also, as used herein, “a number of” a particular elementand/or feature can refer to one or more of such elements and/orfeatures.

FIG. 1 illustrates a perspective view of a portion of a memory array 100in accordance with a number of embodiments of the present disclosure. Inthis example the array 100 is a cross-point array 100 including memorycells 106 at the intersections of a first number of conductive lines102-0, 102-1, . . . , 102-N, e.g., access lines, which may be referredto herein as word lines, and a second number of conductive lines 104-0,104-1, . . . , 104-M, e.g., data lines, which may be referred to hereinas bit lines. Coordinate axis 101 indicates that the bit lines 104-0,104-1, . . . , 104-M are oriented in an x-direction and the word lines102-0, 102-1, . . . , 102-N are oriented in a y-direction, in thisexample. As illustrated, the word lines 102-0, 102-1, . . . , 102-N aresubstantially parallel to each other and are substantially orthogonal tothe bit lines 104-0, 104-1, . . . , 104-M, which are substantiallyparallel to each other; however, embodiments are not so limited. As usedherein, the term “substantially” intends that the modifiedcharacteristic needs not be absolute, but is close enough so as toachieve the advantages of the characteristic. For example,“substantially parallel” is not limited to absolute parallelism, and caninclude orientations that are at least closer to a parallel orientationthan a perpendicular orientation. Similarly, “substantially orthogonal”is not limited to absolute orthogonalism, and can include orientationsthat are at least closer to a perpendicular orientation than a parallelorientation.

The cross-point array 100 can be an array structure such as thatdescribed below in connection with FIGS. 3 and 4, for instance. As anexample, the memory cells 106 can be phase change random access memory(PCRAM) cells, resistive random access memory (RRAM) cells, conductiverandom access memory (CBRAM) cells, and/or spin transfer torque randomaccess memory (STT-RAM) cells, among other types of memory cells. Invarious embodiments, the memory cells 106 can have a “stack” structurethat includes a select device, e.g., a switching device, coupled inseries to a storage element, e.g., a resistive storage elementcomprising a phase change material or metal oxide. As an example, theselect device can be a diode, field effect transistor (FET), a bipolarjunction transistor (BJT), or an ovonic threshold switch (OTS), amongother switching elements.

In a number of embodiments, the select device and storage elementassociated with the respective memory cells 106 can be series coupledtwo-terminal devices. For instance, the select device can be atwo-terminal OTS, e.g., a chalcogenide alloy formed between a pair ofelectrodes, and the storage element can be a two-terminal phase changestorage element, e.g., a phase change material (PCM) formed between apair of electrodes. Memory cells 106 including a switching element suchas an OTS in series with a PCM can be referred to as a phase changematerial and switch (PCMS) memory cells. In a number of embodiments, anelectrode can be shared between the select device and storage element ofthe memory cells 106. Also, in a number of embodiments, the bit lines104-0, 104-1, . . . , 104-M and the word lines 102-0, 102-1, . . . ,102-N can serve as top or bottom electrodes corresponding to the memorycells 106.

As used herein, a storage element can refer to a programmable portion ofa memory cell 106, e.g., the portion programmable to a number ofdifferent data states. For example, in PCRAM and RRAM cells, a storageelement can include the portion of the memory cell having a resistancethat is programmable to particular levels corresponding to particulardata states responsive to applied programming signals, e.g., voltageand/or current pulses, for instance. A storage element can include, forinstance, one or more resistance variable materials such as a phasechange material. As an example, the phase change material can be achalcogenide alloy such as an indium(In)-antimony(Sb)-tellurium(Te)(IST) material, e.g., In₂Sb₂Te₅, In₁Sb₂Te₄, In₁Sb₄Te₇, etc., or agermanium(Ge)-antimony(Sb)-tellurium(Te) (GST) material, e.g.,Ge₈Sb₅Te₈, Ge₂Sb₂Te₅, Ge₁Sb₂Te₄, Ge₁Sb₄Te₇, Ge₄Sb₄Te₇, or etc., amongother phase change materials. The hyphenated chemical compositionnotation, as used herein, indicates the elements included in aparticular mixture or compound, and is intended to represent allstoichiometries involving the indicated elements. Other phase changematerials can include Ge—Te, In—Se, Sb—Te, Ga—Sb, In—Sb, As—Te, Al—Te,Ge—Sb—Te, Te—Ge—As, In—Sb—Te, Te—Sn—Se, Ge—Se—Ga, Bi—Se—Sb, Ga—Se—Te,Sn—Sb—Te, In—Sb—Ge, Te—Ge—Sb—S, Te—Ge—Sn—O, Te—Ge—Sn—Au, Pd—Te—Ge—Sn,In—Se—Ti—Co, Ge—Sb—Te—Pd, Ge—Sb—Te—Co, Sb—Te—Bi—Se, Ag—In—Sb—Te,Ge—Sb—Se—Te, Ge—Sn—Sb—Te, Ge—Te—Sn—Ni, Ge—Te—Sn—Pd, and Ge—Te—Sn—Pt, forexample. Other examples of resistance variable materials includetransition metal oxide materials or alloys including two or more metals,e.g., transition metals, alkaline earth metals, and/or rare earthmetals. Embodiments are not limited to a particular resistive variablematerial or materials associated with the storage elements of the memorycells 106. For instance, other examples of resistive variable materialsthat can be used to form storage elements include binary metal oxidematerials, colossal magnetoresistive materials, and/or various polymerbased resistive variable materials, among others.

Although not illustrated in FIG. 1, in a number of embodiments, thearray 100 can be part of a three dimensional (3D) architecture, with anumber of arrays 100 vertically stacked on each other. In suchembodiments, conductive lines such as 104-0, 104-1, . . . , 104-M canserve as a bit line for one level of the 3D array and as a word line fora subsequent level of the 3D array, for instance. Also, although notillustrated in FIG. 1, the word lines 102-0, 102-1, . . . , 102-N can becombined conductive plug/word lines such as those described below inconnection with FIGS. 3 and 4. Additionally, the array 100 can becoupled to array circuitry, e.g., decode circuitry among various othercircuitry associated with operating array 100. Such array circuitry canunderly array 100, for instance.

In operation, the memory cells 106 of array 100 can be programmed byapplying a voltage, e.g., a write voltage, across the memory cells 106via selected conductive lines, e.g., word lines 102-0, 102-1, . . . ,102-N and bit lines 104-0, 104-1, . . . , 104-M. The width and/ormagnitude of the voltage pulses across the memory cells 106 can beadjusted, e.g., varied, in order to program the memory cells 106 toparticular logic states, e.g., by adjusting a resistance level of thestorage element.

A sensing, e.g., read, operation can be used to determine the logicstate of a memory cell 106. For instance, particular voltages can beapplied to a bit line 104-0, 104-1, . . . , 104-M and word line 102-0,102-1, . . . , 102-N corresponding to a selected memory cell 106, andcurrent through the cell responsive to a resulting voltage differencecan be sensed. Sensing operations can also include biasing unselectedword lines and bit lines, e.g., word lines and bit lines coupled tonon-selected cells, at particular voltages in order to sense the logicstate of a selected cell 106.

As an example, the array 100 can be operated in accordance with a halfselect method, e.g., a half select biasing scheme. A half select methodcan include applying a half select voltage (V/2) to a selected bit line,e.g., a bit line coupled to a selected memory cell, and a negative halfselect voltage (−V/2) to a selected word line, e.g., a word line coupledto the selected memory cell, while biasing unselected word lines and bitlines at a reference potential, e.g., a ground potential. As such, afull select voltage (V) is applied across the selected memory cell. Inthis example, the unselected memory cells coupled to the selected bitline and selected word line experience a half select voltage of +/−V/2and can be referred to as “half selected” cells. The select devices canallow current through selected memory cells, e.g., cells experiencingthe full select voltage (V), while blocking or limiting current throughunselected cells coupled to a selected word line and bit line, e.g.,cells experiencing the half select voltage. In this example, unselectedmemory cells coupled to unselected bit lines and/or word lines areunbiased, e.g., they experience a ground potential of 0V, in thisexample. The select voltage (V) can be a write voltage or a readvoltage, for instance. Embodiments of the present disclosure are notlimited to a half select method associated with programming or readingcells of array 100. For instance, the array 100 can be operated inaccordance with other biasing schemes, such as a one third selectmethod, among other biasing schemes.

FIG. 2 illustrates a cross-sectional view of a portion of a memory array207 formed in accordance with a prior art method. For referencepurposes, FIG. 2 can represent a cross-section taken along they-direction (word line direction) through a memory cell 106 shown inFIG. 1.

Array 207 includes a memory cell 206 formed on a substrate 220. As usedin the present disclosure, the term “substrate” can includesilicon-on-insulator (SOI) or silicon-on-sapphire (SOS) technology,doped and undoped semiconductors, epitaxial layers of silicon supportedby a base semiconductor foundation, conventional metal oxidesemiconductors (CMOS), e.g., a CMOS front end with a metal backend,and/or other semiconductor structures and technologies. Variouscircuitry, such as decode circuitry, for instance, associated withoperating memory array 207 can be formed in/on substrate 220.Furthermore, when reference is made to a “substrate” in the followingdescription, previous process steps may have been utilized to formregions or junctions in the base semiconductor structure or foundation.

The array 207 includes a conductive plug 213, which can serve toelectronically couple a conductive line 202, e.g., word line, of thearray 207 to underlying circuitry, e.g., decode circuitry (not shown),formed in/on substrate 220. The conductive plug 213 can be formed byetching a via in a dielectric material 209 formed on substrate 220 andfilling the via with a conductive material, which can comprise tungsten,titanium, platinum, nickel, strontium, hafnium, zirconium, tantalum,aluminum, oxides and nitrides thereof, and combinations thereof, amongvarious other conductive and/or semiconductive metals, for instance. Theplug 213 and/or conductive line 202 can be formed via a number ofdeposition processes, e.g., physical vapor deposition (PVD), chemicalvapor deposition (CVD), and/or atomic layer deposition (ALD), amongothers.

FIG. 2 illustrates a conductive material 202 formed on the dielectricmaterial 209 and conductive plug 213. The conductive material 202 can beformed into a conductive line 202, e.g., word line, via subsequentprocessing steps (not shown), e.g., masking and etching. The conductiveline 202 can comprise a metal material such as tungsten, titanium, andtitanium nitride, and/or other conductive materials suitable for servingas a conductive line, e.g., word line and/or bit line, for the array207.

In various previous approaches such as that illustrated in FIG. 2, theconductive plug 213 is planarized, e.g., via CMP, to provide a suitablecontact interface 224 with the subsequently formed conductive line 202.As such, formation of the plug 213 and line 202 occur via separate anddistinct deposition processes, with a CMP performed in between.Therefore, although the conductive plug 213 and conductive line 202 maycomprise the same conductive material, they are formed via separatedeposition processes such that an inter-metallic interface 224 existsbetween them. As noted above, such an interface, e.g., 224, can increasethe path resistance associated with a memory cell, e.g., 206, ascompared to embodiments of the present disclosure, which can adverselyeffect the operation thereof. Furthermore, performing separatedeposition processes with a CMP therebetween to form plug 213 and line202 can be time consuming, e.g., due to the performance of two separatedepositions processes, and/or costly, e.g., CMP consumables areexpensive.

The memory cell 206 can be a memory cell such as cell 106 described inFIG. 1. For instance, the memory cell 206 includes a select device 210in series with a storage element 212 and formed between conductive line202 and a conductive line 204, e.g., a bit line. Although the selectdevice 210 is located below the storage element 212, embodiments are notso limited. For instance, the select device 210 can be located above thestorage element 212, in a number of embodiments. As an example, thememory cell 206 can be a PCMS cell 206. For instance, the select device210 can be an ovonic threshold switch (OTS) 210 and the storage element212 can be a phase change storage element 212.

Although not shown in FIG. 2, the OTS 210 can comprise an OTS material,e.g., a chalcogenide alloy, formed between a pair of electrodes, e.g.,electrodes located at interfaces 216 and 217, and the phase changestorage element can comprise a phase change material, e.g., achalcogenide alloy, formed between a pair of electrodes, e.g.,electrodes formed at interfaces 217 and 218. In such embodiments, theelectrodes can comprise various conductive and/or semiconductivematerials such as materials including carbon, for instance. In a numberof embodiments, the OTS 210 and phase change storage element 212 canshare an electrode, e.g., a shared electrode at interface 217. Also, ina number of embodiments, the conductive lines 202 and/or 204 can serveas electrodes for the select device 210 and storage element 212 or theelectrodes at interfaces 216 and/or 218 can be integrated with theconductive lines 202 and 204, respectively.

FIG. 3 illustrates a cross-sectional view of a portion of a memory array303 formed in accordance with a number of embodiments of the presentdisclosure. For reference purposes, FIG. 3 can represent a cross-sectiontaken along the y-direction (word line direction) through a memory cell106 shown in FIG. 1.

Array 303 includes a memory cell 306 formed on a substrate 320, whichcan be analogous to substrate 220 described above in connection withFIG. 2. As such, various circuitry, such as decode circuitry, forinstance, associated with operating memory array 303 can be formed in/onsubstrate 320.

In contrast to the array 207 described in connection with FIG. 2, thearray 303 includes a combined, e.g., integrated, conductiveplug/conductive line 322, which can serve to electrically couple memorycell 306 to array circuitry, e.g., decode circuitry 420 shown in FIG. 4,associated with operating, e.g., programming, reading, erasing, etc.,the array 303. The combined conductive plug/conductive line 322 includesa plug portion 323 and a line portion 325. In a number of embodiments,the combined conductive plug/conductive line 322 is formed of acontinuous conductive material, or materials, such that an interfacedoes not exist between the plug portion 323 and the line portion 325,e.g., an interface such as interface 224 between conductive line 202 andplug 213 shown in FIG. 2 does not exist. As such, unlike previousapproaches, in a number of embodiments of the present disclosure, a CMPprocess is not performed between formation of the plug portion 323 andline portion 325, since the integrated conductive plug/conductive line322 serves as both a conductive line of the array 303 and a conductiveplug coupling the conductive line to underlying decode circuitry, forinstance. That is, formation of the integrated conductiveplug/conductive line 322 does not occur via separate and distinctdeposition processes, with a CMP performed in between, such as thatdescribed in connection with FIG. 2. As such, the integrated conductiveplug/conductive line 322 can provide a reduced path resistanceassociated with memory cell 306, as compared to memory cell 206, amongother benefits.

The integrated conductive plug/conductive line 322 can serve as a wordline or a bit line corresponding to memory cell 306, for instance. As anexample, the integrated conductive plug/conductive line 322 can beformed by etching a via in a dielectric material 309 fowled on substrate320 and subsequently forming a conductive material on the material 309and in the via. The substrate 320 and dielectric material 309 can becollectively referred to as a substrate structure, for instance. Theconductive material 322 can be formed into one or more individualconductive line portions 325 via subsequent processing steps (notshown), e.g., via masking and etching subsequent to deposition of amaterial stack on the conductive material 322.

The conductive material 322 can comprise tungsten, titanium, platinum,nickel, strontium, hafnium, zirconium, tantalum, aluminum, oxides andnitrides thereof, and combinations thereof, among various otherconductive and/or semiconductive metals, for instance. The conductivematerial 322 can be formed via a number of deposition processes, e.g.,physical vapor deposition (PVD), chemical vapor deposition (CVD), and/oratomic layer deposition (ALD), among others. In a number of embodiments,forming the conductive material 322 can include performing amulti-material deposition process. For instance, the conductive materialcan be formed via a multi-material deposition process that includes atleast two of tungsten, titanium, and titanium nitride. In a number ofembodiments, a multi-material deposition process can include depositionof materials using at least two different deposition processes. Forexample, a first conductive material, e.g., titanium, can be depositedvia a PVD process, and a second material, e.g., titanium nitride, can bedeposited via a CVD process. However, embodiments are not so limited.For instance, in a number of embodiments, the integrated conductiveplug/conductive line 322 can be formed via a single deposition processand/or can comprise one particular material. As one example, theintegrated conductive plug/conductive line 322 can be formed via PVDdeposition of tungsten.

The memory cell 306 can be a memory cell such as cell 106 described inFIG. 1 or memory cell 206 described in FIG. 2. For instance, the memorycell 306 includes a select device 310 in series with a storage element312 and formed between conductive line 302 and an integrated conductiveplug/conductive line 322. Although the select device 310 is locatedbelow the storage element 312, embodiments are not so limited. Forinstance, the select device 310 can be located above the storage element312, in a number of embodiments. As an example, the memory cell 306 canbe a PCMS cell 306. For instance, the select device 310 can be an ovonicthreshold switch (OTS) 310 and the storage element 312 can be a phasechange storage element 312.

Although not shown in FIG. 3, the OTS 310 can comprise an OTS material,e.g., a chalcogenide alloy, formed between a pair of electrodes, e.g.,electrodes located at interfaces 316 and 317, and the phase changestorage element can comprise a phase change material, e.g., achalcogenide alloy, formed between a pair of electrodes, e.g.,electrodes formed at interfaces 317 and 318. In such embodiments, theelectrodes can comprise various conductive and/or semiconductivematerials such as materials including carbon, for instance. In a numberof embodiments, the OTS 310 and phase change storage element 312 canshare an electrode, e.g., a shared electrode at interface 317. Also, ina number of embodiments, the integrated conductive plug/conductive line322 and/or the conductive line 304 can serve as electrodes for theselect device 310 and storage element 312 or the electrodes atinterfaces 316 and/or 318 can be integrated with the integratedconductive plug/conductive line 322 and the conductive line 204,respectively.

In a number of embodiments, a CMP process can be utilized after theformation of the conductive line/conductive plug 322 to prepare acontact surface thereof for subsequent processing steps, e.g., formationof select device 310 thereon, etc. However, as described above, sinceplug portion 323 is not formed separately from line portion 325, nointerface exists between them. As such, unlike in the previous approachdescribed in connection with FIG. 2, no CMP process is performed betweenformation of the plug portion 323 and line portion 325 of the integratedplug/line 322.

FIG. 4 illustrates a portion of a memory array formed in accordance witha number of embodiments of the present disclosure. The array structureshown in FIG. 4 can represent the array 303 shown in FIG. 3 at aparticular process stage, e.g., prior to definition of a number ofindividual conductive lines such as word lines and/or bit lines.

FIG. 4 illustrates array circuitry 420, e.g., decode circuitry, coupledto a combined conductive line/conductive plug material 422 such asmaterial 322 described in FIG. 3. A stack of materials 410, 412, and 421is formed on the combined conductive line/conductive plug material 422.As an example, the material 410 can comprise active select devicematerial, e.g., a switching material such as an OTS material, thematerial 412 can comprise an active storage element material, e.g., aresistance variable material such as a PCM material, and the material421 can comprise a hard mask material, e.g., a silicon nitride materialor other material suitable for serving as a hard mask material duringsubsequent processing steps, e.g., etching.

As an example, although not illustrated in FIG. 4, individual conductivelines can be defined by patterning, e.g., in the y-direction, andforming a number of trenches through the material stack comprisingmaterials 421, 412, 410, and 422, e.g., via a dry etch process. Theconductive lines formed via the patterning and etching process can becombined conductive line/conductive plugs such as combined conductiveline/conductive plugs 322 shown in FIG. 3. The combined conductiveline/conductive plugs formed of material 422 do not include an interfacebetween a conductive plug portion 423 and a conductive line portionthereof.

Although not illustrated in FIG. 4, after filling with dielectrics andplanarization down to the top of the material stack, a conductive linematerial can then be formed on the material stack and the stack can bepatterned and etched, e.g., in the x-direction, thereby defining anumber of conductive lines, e.g., bit lines such as bit line 304 shownin FIG. 3, and cell stacks, e.g., cells 306 shown in FIG. 3.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anarrangement calculated to achieve the same results can be substitutedfor the specific embodiments shown. This disclosure is intended to coveradaptations or variations of various embodiments of the presentdisclosure. It is to be understood that the above description has beenmade in an illustrative fashion, and not a restrictive one. Combinationof the above embodiments, and other embodiments not specificallydescribed herein will be apparent to those of skill in the art uponreviewing the above description. The scope of the various embodiments ofthe present disclosure includes other applications in which the abovestructures and methods are used. Therefore, the scope of variousembodiments of the present disclosure should be determined withreference to the appended claims, along with the full range ofequivalents to which such claims are entitled.

In the foregoing Detailed Description, various features are groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the disclosed embodiments of the presentdisclosure have to use more features than are expressly recited in eachclaim. Rather, as the following claims reflect, inventive subject matterlies in less than all features of a single disclosed embodiment. Thus,the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment.

1. A method for forming a memory array, comprising: forming a substratestructure including array circuitry; forming a number of vias in thesubstrate structure such that a number of portions of the arraycircuitry are exposed; and forming a conductive material in the numberof vias and on the substrate structure, the conductive material to serveas a number of conductive lines of the array and coupling the number ofconductive lines to the array circuitry.
 2. The method of claim 1,further comprising, forming a material stack on the conductive material,and defining the number of conductive lines of the array by removingportions of the material stack and portions of the conductive materialformed on the substrate structure.
 3. The method of claim 2, furthercomprising, performing a planarization process on the conductivematerial prior to forming the material stack thereon.
 4. The method ofclaim 1, wherein forming the conductive material in the number of viasand on the substrate structure includes performing a multi-materialdeposition process.
 5. The method of claim 4, wherein performing themulti-material deposition process includes depositing at least twomaterials selected from the group including: Tungsten; Titanium; andTitanium nitride.
 6. The method of claim 4, wherein performing themulti-material deposition process includes depositing at least onematerial via a physical vapor deposition (PVD) process and depositing atleast one material via a chemical vapor deposition (CVD) process.
 7. Themethod of claim 6, including depositing titanium via the PVD process anddepositing titanium nitride via the CVD process.
 8. The method of claim1, wherein forming the conductive material in the number of vias and onthe substrate structure forms a respective number of conductive plugsbetween the array circuitry and the number of conductive lines, whereinan interface does not exist between the conductive lines and therespective number of conductive plugs.
 9. The method of claim 1, whereinforming the memory device includes forming a cross-point array of memorycells each including a phase change resistive storage element in serieswith an ovonic threshold switch (OTS).
 10. The method of claim 1,wherein forming the conductive material in the number of vias and on thesubstrate structure includes performing a single physical vapordeposition of tungsten.
 11. A method for forming a memory array,comprising: forming a substrate structure including array circuitry;forming a via in the substrate structure such that a portion of thearray circuitry is exposed; forming a combined conductiveplug/conductive line by forming a conductive material in the via and onthe substrate structure such that there is not an interface between aplug portion and a line portion of the combined conductiveplug/conductive line; forming a material stack on the conductivematerial; and defining a number of conductive lines of the array byremoving portions of the material stack and portions of the conductivematerial formed on the substrate structure.
 12. The method of claim 11,wherein the combined conductive plug/conductive line serves as a wordline of the array and couples the word line to decode circuitry of thearray.
 13. The method of claim 11, including forming the combinedconductive plug/conductive line via a single deposition of theconductive material.
 14. The method of claim 11, wherein the materialstack comprises a select device material and a resistive storage element(RSE) material.
 15. A memory array, comprising: a memory cell comprisinga select device and a resistive storage element (RSE) formed between afirst conductive line and a second conductive line; and a conductiveplug coupling the first conductive line to array circuitry; wherein theconductive plug and the first conductive line are formed of a continuousconductive material, such that an interface does not exist between theconductive plug and the first conductive line.
 16. The memory array ofclaim 15, wherein the array circuitry comprises decode circuitry. 17.The memory array of claim 15, wherein the select device and the RSE aretwo-terminal devices.
 18. The memory array of claim 17, wherein theselect device is an ovonic threshold switch (OTS).
 19. The memory arrayof claim 17, wherein the RSE comprises a chalcogenide alloy.
 20. Thememory array of claim 15, wherein the first conductive line is at leastone of: a word line; and a bit line.
 21. A memory array, comprising: amemory cell comprising a select device and a resistive storage element(RSE) formed between a first conductive line and a combined conductiveplug/conductive line; and the combined conductive plug/conductive lineincluding: a plug portion formed in a via and coupling to arraycircuitry; and a line portion serving as at least one of: a word lineand a bit line of the array; wherein the combined conductiveplug/conductive line is formed of a continuous conductive material, suchthat an interface does not exist between the plug portion and the lineportion of the combined conductive plug/conductive line.
 22. The memoryarray of claim 21, wherein the conductive material is a metallizationcomprising physical vapor deposition (PVD) Titanium (Ti) and chemicalvapor deposition (CVD) Titanium Nitride (TiN).
 23. The memory array ofclaim 21, wherein the conductive material is Tungsten (W).
 24. Thememory array of claim 21, wherein the conductive line is a bit line andthe line portion of the combined conductive plug/conductive line is aword line.
 25. The memory array of claim 21, wherein the conductivematerial comprises at least two materials selected from the groupincluding: Tungsten; Titanium; and Titanium nitride.
 26. The memoryarray of claim 21, wherein the array circuitry comprises decodecircuitry.